A mixed mode CD is a
compact disc
The compact disc (CD) is a Digital media, digital optical disc data storage format co-developed by Philips and Sony to store and play digital audio recordings. It employs the Compact Disc Digital Audio (CD-DA) standard and was capable of hol ...
which contains both data and audio in one
session.
[PCMAG.com Mixed Mode CD Definition](_blank)
/ref> Typically the first track is a data track while the rest are audio tracks. The most common use for mixed mode CDs is to add CD-quality audio to video game
A video game or computer game is an electronic game that involves interaction with a user interface or input device (such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device) to generate visual fe ...
s on a CD.
The term "enhanced CD" is sometimes used to refer to mixed mode CDs,[Enhanced CD Formats](_blank)
/ref> though it is most commonly used to refer to either a more general category of formats that mix audio and data tracks, or to the particular Enhanced Music CD
The Blue Book is a compact disc standard developed in 1995 by Philips and Sony. It defines the Enhanced Music CD format (E-CD, also known as CD-Extra, CD-Plus and CD+), which combines CD-DA, audio tracks and CD-ROM, data tracks on the same disc. T ...
format.
Overview
Mixed mode CDs are implicitly described in the original CD-ROM
A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains computer data storage, data computers can read, but not write or erase. Some CDs, called enhanced CDs, hold b ...
standard (the ''Yellow Book'', later standardized as ISO/IEC 10149 and ECMA-130), which allows a CD-ROM to contain only data tracks, or data tracks and audio tracks. The CD-ROM standard, however, does not mention the term "mixed mode", nor does it describe any particular order of data and audio tracks on the disc. Since the original CD-ROM standard did not support multiple sessions, mixed mode CDs are created using only one session.
Some CD players manufactured prior to the mid-to-late-1990s have trouble with the mixed mode CD format because the first track, which contains data, might be "played", resulting in screeching which, at worst, might damage speakers. This is caused by the player not recognizing the "data" flag bit for the track that distinguishes it from an audio track; these players were designed for audio CDs only, with no provisions to handle CD-ROMs with both data and audio tracks. As a result, it attempts to play back the data file as an audio recording, converting the encoded data into incongruous noise that can exceed the limitations of commercial speakers. Newer audio CD players do check for data tracks and (at least) mute the track if it contains data and not audio.
Several newer formats were created to improve the usability of CDs with audio and data tracks in audio CD players; these formats include CD-i, CD-i Ready, and Enhanced CDs (both Blue Book-standard and non-standard enhanced CDs). In the case of the latter, audio tracks are placed in one session before the data tracks, which are stored in a second session. This avoids the problem with the data track for most audio players, since they will only be able to recognize the first session.
Use in video games
Most games released for the Mega-CD/Sega CD and NEC PC Engine CD/TurboGrafx CD are mixed mode CDs. Several games for the PC, Amiga
Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-b ...
, PlayStation
is a video gaming brand owned and produced by Sony Interactive Entertainment (SIE), a division of Japanese conglomerate Sony. Its flagship products consists of a series of home video game consoles produced under the brand; it also consists ...
, Sega Saturn
The is a home video game console developed by Sega and released on November 22, 1994, in Japan, May 11, 1995, in North America, and July 8, 1995, in Europe. Part of the fifth generation of video game consoles, it is the successor to the succes ...
, and Dreamcast
The is the final home video game console manufactured by Sega. It was released in Japan on November 27, 1998, in North America on September 9, 1999 and in Europe on October 14, 1999. It was the first sixth-generation video game console, prec ...
are mixed mode CDs as well. Games ported from floppy disk
A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...
or cartridge media to a CD would often have the music replaced with (Red Book) audio CD tracks, using the mixed-mode format.
As an alternative, some games embed video and audio in CD-ROM
A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains computer data storage, data computers can read, but not write or erase. Some CDs, called enhanced CDs, hold b ...
data files and tend not to use CD audio tracks in the game, usually taking advantage of XA interleaving. This was the norm for and including Full-motion video (FMV) games, as the CD drive speed and system RAM size were not adequate to pre-load the video from the disc completely into RAM before playing it, so it had to be played (streamed) directly from the disc, and the CD drive could not read two tracks (a data track containing the video, and an audio track) at the same time.
A short Red Book audio track was sometimes included with non-mixed-mode games anyway, so that when these discs are played in a CD player, the player will reproduce a recorded warning announcement, typically stating that the disc is not meant to be run in an audio CD player before instructing the listener to eject the disc immediately. Bonus audio tracks might also be included on the disc as Easter eggs
Easter eggs, also called Paschal eggs, are eggs that are Egg decorating, decorated for the Christian holiday of Easter, which celebrates the resurrection of Jesus. As such, Easter eggs are commonly used during the season of Eastertide (Easter ...
for the player to find when the game software is not running.[An example is the last track on the '' Sewer Shark'' pack-in game CD for the Sega CD, which is a sort of audio " vanity plate" for Digital Pictures, the producers of the game.]
References
{{Rainbow Books
Compact disc
pl:Mixed-Mode